U.S. patent application number 11/477764 was filed with the patent office on 2008-02-14 for traffic monitoring.
This patent application is currently assigned to NOKIA CORPORATION. Invention is credited to Serge Haumont.
Application Number | 20080039032 11/477764 |
Document ID | / |
Family ID | 38565532 |
Filed Date | 2008-02-14 |
United States Patent
Application |
20080039032 |
Kind Code |
A1 |
Haumont; Serge |
February 14, 2008 |
Traffic monitoring
Abstract
Embodiments of the invention include a method comprising
monitoring a traffic pattern relating to a terminal, and regulating
states of the terminal according to the monitored traffic pattern.
Other embodiments relate to associated apparatus, communication
systems, network elements and computer program products.
Inventors: |
Haumont; Serge; (Helsinki,
FI) |
Correspondence
Address: |
SQUIRE, SANDERS & DEMPSEY L.L.P.
14TH FLOOR, 8000 TOWERS CRESCENT
TYSONS CORNER
VA
22182
US
|
Assignee: |
NOKIA CORPORATION
|
Family ID: |
38565532 |
Appl. No.: |
11/477764 |
Filed: |
June 30, 2006 |
Current U.S.
Class: |
455/115.1 |
Current CPC
Class: |
Y02D 70/1226 20180101;
Y02D 30/70 20200801; Y02D 70/1242 20180101; H04W 52/0216 20130101;
Y02D 70/1262 20180101; H04W 8/22 20130101; Y02D 70/1224 20180101;
Y02D 70/146 20180101 |
Class at
Publication: |
455/115.1 |
International
Class: |
H04B 17/00 20060101
H04B017/00 |
Claims
1. A method comprising: a) monitoring a traffic pattern relating to
a terminal; and b) regulating states of the terminal according to
the monitored traffic pattern.
2. A method according to claim 1, wherein the step of regulating
states comprises setting a timer of the terminal.
3. A method according to claim 1, wherein the monitored traffic
pattern comprises a keep alive message pattern relating to the
terminal.
4. A method according to claim 1, wherein the terminal is a mobile
terminal.
5. A method according to claim 1, further comprising storing data
indicative of the monitored traffic pattern in a node in a
telecommunications system.
6. A method according to claim 5, wherein the data is stored in a
first controller node having a connection with the terminal.
7. A method according to claim 6, further comprising transmitting
the data to a second controller node when the terminal establishes
a connection with the second controller node.
8. A method according to claim 2, wherein the setting of the timer
defines a period after which the terminal shifts to a state having
a lower power consumption, if the terminal is inactive during the
period.
9. A method according to claim 8, wherein if the frequency of keep
alive messages decreases, a length of the period is increased.
10. A method according to claim 8, wherein if the frequency of keep
alive messages increases, a length of the period is decreased.
11. A method according to claim 1, wherein the traffic pattern is
monitored by a controller node in the telecommunications system
having a connection with the terminal.
12. A method according to claim 11, wherein the controller node
sends an indication of an timer setting to the terminal in an
attach accept message, a routing area accept message or a dedicated
timer modification message.
13. A method according to claim 1, further comprising monitoring
mobility of the terminal.
14. A method according to claim 13, comprising setting a timer
according to the monitored mobility of the terminal and the
monitored traffic pattern of the terminal.
15. A method according to claim 13, wherein if mobility of the
terminal decreases, a length of a period of inactivity after which
the timer expires is increased.
16. A method according to claim 1, wherein the monitored traffic
pattern comprises a level of paging traffic associated with the
terminal.
17. A method according to claim 1, further comprising setting a
periodic routing area update timer for the terminal according to
the monitored traffic pattern and/or mobility of the terminal.
18. An apparatus configured to: a) monitor a traffic pattern
relating to a terminal; and b) regulate states of the terminal
according to the monitored traffic pattern.
19. An apparatus according to claim 17, which is configured to
regulate states by setting a timer of the terminal.
20. An apparatus according to claim 17, which is a SGSN or radio
network controller.
21. An apparatus according to claim 17,
22. A communications system comprising a terminal and a network
node, wherein the system is configured to: a) monitor a traffic
pattern relating to a terminal; and b) regulate states of the
terminal according to the monitored traffic pattern.
23. A communications system according to claim 2, configured to
regulate states of the terminal by setting an inactivity timer of
the terminal according to the monitored traffic pattern.
24. A network element comprising: monitoring means for monitoring a
traffic pattern relating to a terminal; and regulating means for
regulating states of the terminal according to the monitored
traffic pattern.
25. A network element according to claim 23, further comprising
storage means for storing data indicative of the monitored traffic
pattern.
26. A computer program product comprising a set of instructions
which when executed by a processor in a network node of a
communications system, causes the network node to monitor a traffic
pattern relating to a terminal, and regulate states of the terminal
according to the monitored traffic pattern.
Description
FIELD
[0001] The present invention relates to the field of
telecommunications, and in particular to methods for conserving
battery power in user equipment and reducing unnecessary signaling
in telecommunications networks.
BACKGROUND
[0002] A communication system can be seen as a facility that
enables communication sessions between two or more entities such as
user equipment and/or other nodes associated with the communication
system. The communication may comprise, for example, communication
of voice, data, multimedia and so on.
[0003] Communication systems providing wireless communication for
user equipment are known. Cellular communication systems are
configured to have a cell structure, and typically they support
communication with user equipment changing locations (mobile
users). The support for communications for mobile users may include
support for handing existing connections from one cell to another
cell. At least routing of calls or communications for a mobile user
in a new cell is typically supported in cellular systems. Some
examples of a cellular system are the Global System for Mobile
Telecommunications (GSM) and UMTS (Universal Mobile
Telecommunication System).
[0004] A communication system may be circuit switched or packet
switched. General Packet Radio Service (GPRS) provides
packet-switched data services for the GSM and UMTS system.
[0005] A technical problem commonly encountered in
telecommunications systems is how to reduce or minimize both power
consumption of terminals and unnecessary signaling in the network.
The issues of power consumption and unnecessary signaling are often
linked due to the fact that signal transmission typically accounts
for a major part of the overall power consumption of a
terminal.
[0006] Reducing power consumption by terminals is particularly
important in mobile telecommunications networks, due to the fact
that mobile terminals are typically battery powered and thus have a
finite power reserve. Excessive power consumption by mobile
terminals can lead to unacceptably short intervals before the
terminal battery needs to be recharged.
[0007] Power consumption of mobile terminals can be a particular
problem when the terminal is running one or more "always-on"
applications. Always-on applications require the terminal to be
constantly attached to a radio network and to be reachable over the
current radio technology. Examples of always-on applications
include push e-mail, instant messaging, and voice and video
telephony.
[0008] Many always-on applications need to transmit or receive
frequent "keep-alive" messages during the idle times in order to
refresh the soft state in the application servers or intermediate
firewalls and Network Address Translation (NAT) devices. The
keep-alive procedures may maintain the MS in states which consume
so much energy that the battery lifetime will no longer be
acceptable. Since IPsec Virtual Private Network (VPN) and Mobile IP
sessions may be used with always-on applications to provide
security and mobility, increasing the power efficiency of these
protocols is particularly important.
[0009] Embodiments of the present invention aim to address one or
more of the above-mentioned problems. In particular, embodiments of
the present invention aim to reduce power consumption and/or
unnecessary signalling by terminals in a communications
network.
SUMMARY
[0010] Accordingly, in one embodiment the present invention
provides a method (e.g. for use in a telecommunications
system).comprising monitoring a traffic pattern relating to a
terminal, and regulating states (e.g. states of the Mobility
Management protocol or of the Radio Ressource Control protocol) of
the terminal according to the monitored traffic pattern.
[0011] In another embodiment, the present invention provides an
apparatus (e.g. a network node in a communications system)
configured to monitor a traffic pattern relating to a terminal, and
regulate states of the terminal according to the monitored traffic
pattern.
[0012] In another embodiment, the present invention provides a
communications system comprising a terminal and a network node,
wherein the communications systems is configured to monitor a
traffic pattern relating to a terminal, and regulate states of the
terminal according to the monitored traffic pattern.
[0013] In another embodiment, the present invention provides a
network element comprising monitoring means for monitoring a
traffic pattern relating to a terminal and regulating means for
regulating states of the terminal according to the monitored
traffic pattern.
[0014] In another embodiment, the present invention provides a
computer program product, comprising a set of instructions which
when executed by a processor in a network node of a communications
system, causes the network node to monitor a traffic pattern
relating to a terminal, and regulate states of the terminal
according to the monitored traffic pattern.
[0015] In another embodiment, the present invention provides a
computer program comprising program code means adapted to perform
any of the steps of a method as described above when the program is
run on a processor.
[0016] In another embodiment, the present invention provides a
computer program product comprising program code means stored in a
computer readable medium, the program code means being adapted to
perform any of the steps of a method as described above when the
program is run on a processor.
[0017] Embodiments of the present invention may advantageously
reduce power consumption and/or unnecessary signalling of terminals
by dynamically adapting states (e.g. Radio Resource Control or
Mobility Management states) of a terminal according to the pattern
of traffic to/from the terminal. In the absence of such dynamic
control, the traffic pattern may greatly affect the amount of time
which a terminal spends in particular radio resource states, which
in turn is highly determinative of the power consumption of the
terminal. According to embodiments of the present invention, the
time spent by the terminal in particular states can be regulated
such that, for example, a power consumption increase due to an
increase in particular types of traffic is minimized. By monitoring
a traffic pattern to/from the terminal, embodiments of the present
invention allow the configuration of states to be tailored to the
activity and particular requirements of the terminal, and the power
consumption of the terminal to be kept within acceptable limits.
This can increase battery life of the terminal, especially in
mobile terminals, as well as freeing radio and SGSN resources.
[0018] In some embodiments of the present invention, the states are
regulated through timers. After a defined period of time during
which the terminal is inactive, e.g. during which the terminal does
not transmit or receive any packet data, the timer expires.
Typically the expiry of the timer causes the terminal to transition
to a new state with a lower power. Setting of the timer involves
defining a length of this period of inactivity before which the
terminal shifts to a less power-consuming state.
[0019] A terminal may have multiple states each having a different
power consumption, and thus there may be multiple inactivity
timers, each of which defines the length of an inactivity period
before which the terminal shifts to a less power-consuming
state.
[0020] In other embodiments, if the frequency of the monitored
traffic events (e.g. keep alive messages) increases, a length of
the timer period (i.e. the period of inactivity after which the
terminal shifts to a less power-consuming state) is decreased. This
is because if a terminal is sending a lot of traffic, such as
frequent keep-alive messages, it would tend to spend more time in
higher power-consuming states and its overall power consumption
would increase. Decreasing the length of one or more timer periods
in this situation minimizes the increase in power consumption by
ensuring that the terminal returns to a lower power state more
quickly after each transmission event (such as sending or receiving
a keep alive message).
[0021] Alternatively, if the frequency of keep alive messages
decreases, a length of the timer setting is increased. This is
because if the terminal is not sending a lot of traffic, its power
consumption will be lower and it is acceptable for it to spend more
time in higher power states.
[0022] Preferably the traffic monitoring step of the present
invention may involve detecting a pattern of transmission of
messages to/from the terminal, wherein the messages serve to
maintain a connection between the terminal and a further node in
the communication system. More preferably the monitored traffic
comprises keep alive messages transmitted to/from the terminal. In
one embodiment the monitoring comprises detecting a frequency of
transmission of messages such as keep alive messages relating to
the terminal.
[0023] Preferably the terminal is a mobile terminal, and the
network is a mobile telecommunications network.
[0024] The monitoring step typically results in a set of data, for
instance in the form of a traffic profile, indicative of the
traffic pattern associated with the terminal. The method preferably
further comprises storing this data or profile in a node in the
telecommunications system. The data may be stored in any suitable
node in the network, for instance in a first controller node having
a connection with the terminal. By controller node is meant any
node which performs control functions relating to a connection
between the terminal and another node. Thus in some embodiments,
the controller node may be a serving GPRS support node (SGSN) or
radio network controller (RNC). The first controller node may be a
node which also performs the monitoring step or may be a different
node in the communication system.
[0025] The method may further comprise transmitting the data to a
second controller node, for instance when the terminal establishes
a connection with the second controller node.
[0026] The traffic pattern may be monitored by any suitable node in
the communications network, for instance a controller node having a
connection with the terminal. Preferably the node performing the
monitoring step is an SGSN or RNC serving the terminal.
[0027] The regulation of the states of the terminal, for instance
the setting of inactivity timers for the terminal, may be performed
by any suitable node in the telecommunications system. In one
embodiment, a controller node (for instance the controller node
which performs the traffic monitoring step) sends an indication of
an inactivity timer setting to the terminal in an attach accept
message, a routing area accept message or a dedicated timer
modification message. In the case of attach accept and routing area
accept messages, the timer setting indication is added to a type of
message which carries other data and would anyway be transmitted
between the terminal and the node. In the case of a dedicated timer
modification message, the timer setting indication is provided in a
message specifically transmitted for the purpose of modifying the
timer.
[0028] In other embodiments, the method further comprises
monitoring mobility of the terminal. For instance, the controller
node may monitor the frequency of cell changes of the terminal.
Mobility of the terminal may then be taken into account when
regulating the states of the terminal, for instance when setting
the inactivity timers, in addition to the traffic pattern (e.g. the
frequency of keep-alive messages) associated with the terminal.
[0029] If mobility of the terminal decreases, the timer setting
(i.e. the length of the inactive period after which the terminal
transitions to a lower power state) is preferably increased. This
is because if the terminal is relatively static (i.e. its location
is not changing), it will not be sending many cell update messages.
Its power consumption will therefore be relatively low (compared to
a terminal which is highly mobile) and an increasing the amount of
time spent in a higher power state is acceptable.
[0030] In some embodiments, monitoring the traffic pattern of a
terminal may include measuring a level of paging traffic associated
with the terminal. In lower power states, a terminal may not be
able to send or receive data without transitioning to a higher
power state. In order for a terminal in a low power state to
receive data, it is often necessary to page the terminal so that it
can shift to a higher power state and receive the data. The amount
of paging traffic may therefore be indicative of the amount of time
which the terminal is spending in lower power states combined with
the frequency with which it is sending/receiving keep alive
messages. Decreasing the timer settings for terminals sending a lot
of keep alive messages according to embodiments of the present
invention may increase the paging traffic, whereas increasing the
timer settings for terminals sending fewer keep alive messages will
tend to reduce paging traffic. Monitoring the level of paging
traffic to a terminal and taking this into account (along with the
keep alive frequency and optionally also the mobility of the
terminal) when setting the timers can help to ensure that the
paging channel does not become overloaded.
[0031] In other embodiments, the monitored traffic data for the
terminal (and optionally further the mobility of the terminal) may
additionally be used in setting the value of a periodic routing
area update timer for the terminal.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] The invention will now be described by way of example only
with reference to the following specific embodiments, in which:
[0033] FIG. 1 shows a packet switched mobile telecommunications
network in an embodiment of the present invention may be
implemented;
[0034] FIG. 2 shows radio resource states, inactivity timers and
battery consumption in a terminal in a 3G mobile network;
[0035] FIG. 3 shows features of a serving GPRS support node in an
embodiment of the present invention.
DETAILED DESCRIPTION OF EMBODIMENTS
[0036] FIG. 1 illustrates schematically an example of a cellular
network supporting packet-switched services in which the present
invention may be implemented. The network 100 may be a 2G GPRS or a
3G GPRS network. Alternatively, the system 100 may be an EDGE/EGPRS
network. Only some of the network elements of a 2G/3G network are
illustrated in FIG. 1.
[0037] The radio access network comprises a number of base station
systems. Each base station system comprises a base station
controller (BSC) 4 and a number of base stations (BS) 5, 6. A
terminal or mobile station (MS) 7 communicates with a base station
5 over a radio interface. The packet-switched core network of the
system 100 comprises a number of GPRS Supporting Nodes (GSN). Each
mobile station registered for packet-switched services has a
serving GSN, called SGSN, 3 which is responsible for controlling
the packet-switched connections to and from the mobile station. The
packet-switched core network is typically connected to further
packet-switched networks via a Gateway GSN (GGSN) 2. Services may
be provided to the mobile station from an application server 1
connected to the GGSN 2.
[0038] In a cellular network, the MS 7 can be in a number of
different states depending if it is transmitting data, or has
transmitted data recently or not. The state has a significant
impact on the power consumption of mobile terminals in the
network.
[0039] In 2G GPRS a terminal can be either in the state Ready (in
which the MS is tracked at cell level) or the state Stand-by (MS
tracked in Routing Area (RA) level, A routing area comprising many
cells). In the ready state, cell updates are required each time the
MS changes cell. In the stand-by state, The MS only needs to send
updates when changing RA and the MS will be paged in the RA in case
of a downlink packet.
[0040] FIG. 2 illustrates the states in a 3G GPRS network. The
terminal is in one of the following states:
[0041] CELL_DCH (Dedicated Channel). The MS is tracked at cell
level. In this state, the current consumption is at its highest,
comparable to the consumption during circuit-switched voice calls.
The current consumption is around 220 mA or higher. The phone has a
dedicated channel, which it does not share with other phones, so
maximum throughput and minimum delay are achieved.
[0042] CELL_FACH (Forward Access Channel). MS tracked at cell
level. In this state, the phone shares the channel with other
phones. This state is used when there is not much traffic to
transmit. The battery consumption is roughly half of the
consumption in the CELL_DCH state. The current consumption is
roughly 120 mA.
[0043] CELL_PCH (Paging Channel). MS tracked at cell level. This
optional state offers the lowest current consumption of around 1-2
percent of the consumption in CELL_DCH state (around 4 mA). If
there are downlink packets for the terminal, the terminal will be
paged. In this state, the terminal is not able to send or receive
packets, but the terminal will have to enter either the CELL_DCH or
CELL_FACH state to send or receive. Not all network implementations
currently use the CELL_PCH state.
[0044] URA_PCH. MS tracked at UTRAN Registration Area (URA) level.
If there are downlink packets for the terminal, the terminal will
be paged in the URA. There are less updates but more paging than
CELL_PCH. This state provides the same benefits as CELL_PCH and
further enhances the battery performance when there is
mobility.
[0045] Idle mode. MS tracked at Routing Area level by the SGSN and
there are no context in RNC. In this state, the phone does not have
an RRC connection, so it is not possible to send or receive packets
in this state. The terminal can still have a PDP context and it can
be reached by paging procedures, after which the terminal can leave
the idle mode and receive downlink packets. However an RRC
connection will have to be established before the downlink packets
can be received.
[0046] State transitions are based either on explicit signaling or
inactivity timers. The timers T1, T2 and T3 are shown in FIG. 1.
The names T1, T2 and T3 are not officially used in 3GPP
specifications but they have established in WCDMA parlance. The
timers are network controlled and managed by the Radio Network
Controller (RNC). The timers are discussed below:
[0047] T1 is an inactivity timer that is used in the CELL_DCH
state. This timer is reset whenever there is traffic. The timer
will expire only after an inactive period of T1, and the terminal
will enter the CELL_FACH state. The shorter the T1 timer, the worse
the user experience will be e.g. in web browsing. The T1 value may
depend on the DCH data rate. The default values used in the Nokia
RNC implementation are 5 seconds for 8-32 kbit/s, 3 seconds for 128
kbit/s, and 2 seconds for data rates greater than 128 kbit/s. In
some networks, significantly longer timers than the Nokia defaults
may be used.
[0048] T2 is an inactivity timer in the CELL_FACH state. If
CELL_PCH is used, the state machine will enter the CELL_PCH state
after an inactivity period of T2. If CELL_PCH is not used, then the
state machine will enter the idle state. The default value in
Nokia's implementation is 2 seconds, but often significantly longer
T2 values are used.
[0049] T3 is a timer used in CELL_PCH (and in the URA_PCH state
that may be introduced in the future). After staying in the
CELL_PCH or URA_PCH for T3 seconds, the RRC connection will be
released. This is typically a very long timer (several minutes or
even tens of minutes).
[0050] The inactivity timers T1 and T2 define the time after which
the phone transitions from the more power-consuming states to less
consuming states. The sum T1+T2 defines the general power
consumption behavior of the device, and the value of T1 has a
significant effect on the perceived performance of several
applications.
[0051] Always-on applications require the terminal to be constantly
attached to a radio network. In order to keep the connection
active, many always-on applications require that frequent
keep-alive messages are transmitted between the terminal and a
server node in the network, for example between the mobile station
7 and the application server 1 shown in FIG. 1
[0052] Transmission of a keep alive message (like any packet) moves
the mobile station into, or maintains the MS in a high power state
(e.g. Ready state in 2G, CELL_DCH or CELL_FACH in 3G).
[0053] It is often assumed that in packet based cellular networks,
after a packet transmission the probability of a new packet
transmission within a short period of time (e.g. up to a few
seconds) is quite high. But this assumption is not true with
respect to keep alive messages.
[0054] Many applications tend to send keep alive message regularly,
but at intervals of 15 seconds to 10 minutes. For example, Skype
sends client originated keep-alive every 60 seconds. Nokia Email
has a keep-alive sent by server every 4 minutes. A VPN client
behind a NAT might send keep-alive every 30 seconds.
[0055] With keep alive intervals within this range, the MS may be
most of the time in an high power state (in 2G GPRS_Ready; in 3G
PMM Connected DCH/FACH), as short data transmissions are
sent/received only at regularly spaced intervals. This uses a lot
of unnecessary battery power. In addition, it requires a lot of
radio signalling (compared to the amount of data transferred) and
thus consumes network resources. Transferring keep alive is not
very cost efficient for operators.
[0056] One way in which this problem could be addressed is by using
timers in the radio optimised for keep-alive. For example, the
length of timers such as T2 can be kept short, e.g. around 2 s.
However these timers may not be optimised for other applications
like browsing. Today operators have asked for T2=120 seconds
probably due to browsing behaviour.
[0057] According to one embodiment of the present invention, radio
and mobility management timers are adapted dynamically depending on
the pattern of traffic used. A node such as an SGSN or RNC controls
timer setting by: [0058] monitoring the traffic pattern of one
subscriber; [0059] detecting a keep alive pattern; [0060] storing
traffic characteristics in a context related to the terminal; and
[0061] adapting timers to fit best the mobile traffic type.
[0062] The traffic characteristics (e.g. TCP keep-alive every 60 s,
MS initiated) are stored in a new field "traffic profile" in the
subscriber context (in SGSN or RNC), and transferred to a new node
due to mobility events (such as inter SGSN RA update; SRNC
relocation).
[0063] The following specific embodiment is discussed with respect
to a 2G GPRS network. In other embodiments, the method can be
applied to a 3G network in a similar way.
[0064] FIG. 4 shows a flow diagram of how one embodiment of the
present invention may be implemented in a GPRS network 100 as shown
in FIG. 1. At step 41, an SGSN 3 sends attach accept and RA update
accept messages to a mobile terminal 7. These messages may include
a ready timer and/or a periodic RA update timer, by which it is
meant that the SGSN 3 indicates to the mobile terminal 7 in one or
more such messages a setting for a length or period for these
timers. The setting of the ready timer, for example, defines the
length of a period of time, after which the terminal shifts from
the ready to the standby state, if the terminal is inactive during
that period.
[0065] For MS who initiate keep-alive regularly, the ready timer
should be kept very short in order to reduce the amount of cell
updates after a transmission. A value of 5 to 10 second should be
appropriate. The drawback of this is that the amount of paging
would increase. The operator could consider reducing the size of
the RA to reduce paging load. A relative short value of the
periodic Routing area update (e.g. 30 minutes) should also be
appropriate (Normally these MS will not perform periodic RA update
due to frequent packet transmission. However, if they move out of
coverage, the periodic RA update will expire and paging will be
suspended. It will save paging capacity). However, such a setting
would not be optimal for other users who are not having regular
keep-alive message.
[0066] Thus according to one embodiment of the present invention,
the SGSN 3 initially (e.g. at attach) sends to the MS 7 a short
Ready timer setting (5-10 seconds) and a short periodic RA Update
timer (20-40 minutes). These timers are set to a value adapted for
users having regular keep-alive.
[0067] At step 42, the SGSN 3 starts to monitor the traffic
pattern, and at step 43 stores in the subscriber specific traffic
profile information related to the usage of keep-alive. In
particular, the mobile station 7 may be sending keep alive messages
to the application server 1 in order to maintain a connection
necessary for the server 1 to provide a service to the MS 7. If the
user is not sending keep-alive messages at or above a predefined
frequency, in the next RAU response the SGSN 3 resets the timers to
a different setting more appropriate for a terminal which is not
sending regular keep-alive messages. For example, the Ready timer
is set to 60 seconds and the periodic RA Update timer is set to 2
hours (see step 44 in FIG. 4).
[0068] The SGSN 3 keeps monitoring the traffic pattern of this
subscriber, as the user might activate a new application on his
phone. At the next RA update the SGSN 3 again sets the timers
appropriately based on the latest traffic pattern of the user. For
instance, if activation of a new application leads to an increase
in the frequency of keep alive messages, the SGSN may decrease the
length of the timer setting (see step 45).
[0069] It should be noted that if the MS 7 is not moving (so no RA
update is triggered by movement) and sending traffic regularly,
(periodic RA update timer never expires), the SGSN 3 may not be
able to modify the timers. Using a small RA size will increase the
probability that the user cross a RA border.
[0070] In certain cases, the SGSN 3 may want to modify the timers,
but may not receive RA updates. In that case, the SGSN 3 sends a
message to the MS 7 to trigger a modification of the timers. This
message may be sent according to a "timer modification procedure",
a dedicated message which can be used to reset the timers and
generate a RA update.
[0071] One way in which to reset the timers would be for the SGSN 3
to detach an MS with a reattach indication. The SGSN 3 may take
into account the load on a paging channel when setting the timers.
The SGSN 3 may for example detect that a paging channel is
overloaded and/or that certain MS 7 generate a lot of paging.
Typically that could be the case if keep-alive is generated from
the server, and the keep-alive intervals are short. In this case
the SGSN 3 detaches the MS 7, forcing it to re-attach and then sets
a longer ready timer (reducing paging load at the expense of cell
update load). Although in this embodiment the power consumption of
the terminal may increase, in certain circumstances it may be
necessary to avoid overloading on the paging channel.
[0072] The method may be controlled by a traffic detection engine
in, for example, an SGSN 3 or BSC/RNC 4. FIG. 3 shows in more
detail the SGSN 3 in which are represented certain features of one
embodiment of the present invention. The SGSN 3 comprises a timer
regulating/setting means 31, which may comprise a transmission
means for sending timer setting messages to the BSC/RNC 4 for
forwarding to the MS 7. The SGSN 3 also comprises a traffic
monitoring means/traffic detection engine 32 which collects the
relevant data relating to the MS 7. The data may be stored in a
traffic profile field along with other data relating to the
subscriber of the MS 7, in a storage means 34 also provided in the
SGSN 3. Processes performed by the SGSN 3 may be controlled by a
suitably programmed processor means 33.
[0073] In one embodiment the traffic detection engine 32 is able to
derive the number and/or frequency of keep-alive messages
transmitted to/from the terminal 7. Different applications running
on a single MS may generate or require their own keep alive
messages. Thus each keep-alive application should have a profile
containing the following information: [0074] keep-alive frequency;
[0075] keep alive direction; [0076] keep-alive L3/L4
characteristics (IP address/port numbers); [0077] paging
frequency.
[0078] In a further embodiment, the SGSN 3 also monitors the
mobility of the user. For example, the SGSN 3 may monitor the
frequency of cell changes. If the user has not changed cell for an
extended period, e.g. at least 24 hours, the SGSN 3 may determine
that the MS 7 is static and increase the ready timer value (the MS
is not sending cell updates so it can stay in the ready state for
longer).
[0079] In one embodiment employing a 2G GPRS network, the timers
are initially set based on traffic profile, but these settings can
be modified or overruled based on mobility data of the terminal,
e.g. if the MS 7 is static.
[0080] In another embodiment, the traffic profile is sent between
nodes during inter SGSN Routing Area Update, Intersystem inter SGSN
RA update, or SRNC relocation. This may be done because it takes
time to determine a traffic pattern (to be accurate it might be
worth waiting for 3 consecutive keep alive messages which can take
10-20 minutes). By sending the traffic profile to a new node with
which the terminal has just established a connection, the new node
can immediately set its timer accordingly.
[0081] Although the above embodiments have been described with
respect to a 2G GPRS network, the method may also be implemented
with timers in 3G networks. In 3G networks such as UMTS and WCDMA,
key timers regulating Radio Resource Control states are controlled
by the RNC. Thus in alternative embodiments employing 3G networks,
an RNC operates the same pattern detection mechanism and modifies
the timers accordingly. In further embodiments implemented in 3G
networks, the pattern detection is performed in a 3G SGSN, and the
results or timers setting are sent to the RNC during RAB
establishment or RAB modification. If the pattern changes (for
instance if the user activates a new application), the SGSN detects
this and sends a RAB modification to the RNC. The RNC then adjusts
its timers.
[0082] Embodiments of the present invention are applicable to all
wireless packet technology, and so may also be applied to WiMAX or
3.9G (also referred to as 3G long-term evolution or 3G LTE)
networks.
[0083] Although in the appended claims the dependant claims refer
only to an independent claim on which they depend, embodiments of
the present invention may encompass any combination of features
disclosed in the claims. In particular, embodiments of the present
invention may comprise features from any two or more dependant
claims in combination with an independent claim on which they
depend.
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